This invention relates generally to mechanical presses. More particularly, the present invention relates to mechanical presses intended to apply a relatively constant, predetermined clamping force upon work pieces regardless of the thickness of the work piece and a method for controlling the relatively constant, predetermined clamping force.
It is generally known to control the amount of pressure (clamping force) applied upon a work piece. A known manner of relatively effectively controlling the pressure applied upon the work piece is through the use of load cells (i.e., pressure sensors). One disadvantage associated with the use of load cells, is that, load cells typically require additional parts, including electronic components, which typically results in both additional cost and additional space requirements.
Another generally known manner of controlling the pressure applied upon a work piece involves the use of an optical sensor or a position sensor that detects the position of at least one part of the press. Depending on the size, i.e., thickness, of the work piece, a consistent level of pressure may be relatively difficult to apply on the work piece. For example, relatively thin work pieces may have relatively low amounts of pressure applied thereon, whereas relatively thick work pieces may have relatively higher amounts of pressure applied thereon.
In binding a plurality of sheets of media, e.g., sheets of paper, having thermally activated adhesive positioned between the sheets, it is generally known to apply both heat and pressure upon the sheets. In this respect, the amount of pressure applied on the sheets of media directly affects the amount of heat transferred between the sheets of media, thus affecting the heat distribution through the media and the activation of the adhesive between the sheets. In one regard, if relatively excessive amounts of pressure are applied onto the sheets of media, the heat transfer between a heat source and the sheets of media may be exceedingly high, thereby resulting in damage to the sheets. For example, the sheets may become burned, thus potentially turning yellow. Otherwise, if a sufficient amount of pressure is not applied to the sheets, thus resulting in poor contact between the heat source and the sheets, as well as between the sheets themselves, the heat from the heat source may not easily flow from one sheet to another, potentially resulting in poor binding of the sheets.
In accordance with one aspect, the present invention pertains to a press for binding media sheets. The press includes a first plate and a second plate, with a space formed between the first plate and the second plate. The space is sufficiently large to enable a plurality of sheets of media to be inserted into the space. The press also includes a DC motor for manipulating a jack device, such that a position of at least one of the first and second plates is varied in response to manipulation of the jack device. A power source is also included for supplying power to the DC motor. A sensor for detecting a value of current flowing from said power source to the DC motor and a controller for controlling power supply to the DC motor are additionally included. The controller is configured to shut off the power supply to the DC motor in response to the value of current reaching a predetermined value. Furthermore, the press also includes a heat source for supplying heat to the first plate and the second plate, such that heat is configured to be transferred to a plurality of sheets insertable into the space between the first plate and the second plate to thereby bind the plurality of sheets together.
According to another aspect, the present invention pertains to a method for binding a plurality of media sheets with a press having a first plate and a second plate spaced from the first plate, with at least one of the first and second plates being movable by operation of a DC motor. In the method, at least an edge of a plurality of media sheets is inserted into the space provided between the first plate and the second plate. The DC motor is supplied with a current from a power source to thereby activate the DC motor to maneuver at least one of the first plate and the second plate in a direction towards the plurality of media sheets. Additionally, the supply of current into the DC motor is controlled and sensed. Furthermore, an amount of pressure applied on the plurality of media sheets by each of the first plate and the second plate is controlled by controlling the amount of current flowing into the DC motor.
According to yet another aspect, the present invention pertains to a method for controlling pressure applied onto a plurality of print media sheets by a print media binding device having a first plate and a second plate, in which at least one of the first and second plates is maneuverable by a DC motor. In the method, at least one of the first and second plates is maneuvered into substantial contact with the plurality of print media sheets. Additionally, a substantially constant pressure is applied on the plurality of print media sheets by the first plate and the second plate by substantially shutting off the current flowing into the DC motor when the current flowing into the DC motor reaches a predetermined level.
According to the principles of the present invention, certain aspects of the invention are capable of achieving certain advantages, including the application of a predetermined amount of clamping force to bind a plurality of media sheets together without suffering from some of the drawbacks and disadvantages associated with known media binding processes.